Rheostat-plate



(No Model.)

J. 1?. BALL.

RHEOSTAT PLATE.

No. 558,252. Patented A r. 14,1896.

Witnesses.

aBrA W Attorney.

UNITED STATES PATENT OFFICE.

JOSEPH P. BALL, OF PHILADELPHIA, PENNSYLVANIA.

RH EOSTAT-PLATE.

SPECIFICATION forming part of Letters Patent No. 558,252, dated April14:, 1896.

Application filed January 27, 1896. Serial No. 576,947- (No model.)

To all whom it may concern:

Be it known that I, JOSEPH P. BALL, a citizen of the United States,residing at Philadelphia, county of Philadelphia, and State ofPennsylvania, have invented a new and use ful Improvement inRheostat-Plates, of which the following is a full, clear, and exactdescription, reference being had to the accompanying drawings, whichform a part of this specification.

My invention relates to rheostatplates or resistance-plates, andparticularly to those wherein a high-resistance wire, connected at oneend with one pole of an electric circuit, is secured to a plate and isin electrical c011- nection at several points along its length withterminals, with each of which an operatinglever is designed to makecontact, whereby a greater or less length of wire, and consequently agreater or less resistance, is thrown into the circuit.

My invention consists, generally speaking, in a plate of non-conductingmaterial having grooves in its lower surface, within which, bent uponitself to form a convolute, is the resistance-wire, the grooves beingvertically disposed and of substantially the width of the thickness ofthe wire, so thatthe wires will be held within the grooves by frictionaleontactthat is, by binding against the walls of the grooves.

My invention also consists in details of construction particularlydescribed hereinafter.

The objects attained by the above construction are: to simplify andcheapen the manufacture of resistance-plates; to obviate the necessityof holding the wire in place by enamel or other material commonlyadapted for that purpose and thereby provide for free expansion andcontraction of the resistance; to facilitate the repair of the wire orthe insertion of a new coil when for any reason it breaks or burns out,and, also, if desired, to place a long length of wire, with or without agreat number of terminals, in a plate of comparatively small area. Theusual construction, which consists in placing the wire on a plate andsurrounding the wire with enamel which adheres to the plate and holdsthe wire in place, is objectionable for the reason that the unequalcontraction and expansion of the enamel and resistance-wire cause thewire to break. The enamel is also liable to cleave and crack, and minuteparticles of dust, &c., settle in the fissures, which interferes stillmore with the free expansion and contraction of the resistance. Repairis troublesome and expensive. I find that I can dispense with aninsulator for this resistance, as the supposed disintegration fromoxidation is of small importance in comparison with the advantages aboveenumerated.

In the drawings, Figure 1 is an inverted plan view of my improvedrheostat-plate, and Fig. 2 a section through line :10 00 of Fig. 1. Fig.3 is a Vertical transverse section through the slots L M in the plate A.

A is a plate of slate or other non-conducting material; B B, thebinding-posts; O, the hand-lever pivoted to the bolt D, which passesthrough the plate into a recess I on the opposite side thereof andengages the nut E, which binds against the bottom of the recess a wireI), connected at its other end to the bindingpost B. By this means thebinding-post B is permanently connected with the pivot end of lever G.The drawings show three other recesses F F F in the bottom of the plate,into each of which projects a bolt G, secured to a contact-plate orterminal H on the face of the plate. The free end of the hand-lever isadapted to pass over and make contact with these terminals.

Grooves of a depth equal to about half the thickness of plate A areformed in the under surface of the plate in the following manner:-

Groove K extends from one side of the plate to recess F, grooves L and Mfrom recess I to recess F, groove N from one side of the plate to recessF and groove 0 from one end of the plate to groove K, intersecting theother grooves. The resistance R, bent or convoluted, as shown, extendsfrom recess F through grooves K, O, and L to recess F, the resistance Rfrom recess F through grooves M, O, and N to recess F The ends of theresistances are secured to plates or washers P, held in place againstthe bottom of the recesses by nuts Q. The resistances R R are preferablya continuous wire, and are so shown, B and R representing merelysections thereof. The resistance-wire is thus in electrical connectionwith all the terminals. To

the plate P in recess F is secured the end of a wire I), connected atits other end to the binding-post B. I have shown two other groovesextending, respectively, from binding-post B to recess I and frombinding-post B to recess F for the ieception of the connecting-wires,although it will be understood that these grooves are unnecessary, asthese wires are not resistance-wires and may extend over the under faceor around the edge of the plate.

When the hand-lever is in contact with the terminal connected directlywith bindingpost B, the current will pass through wire I), lever C, andout by wire Z). hen the handlever is brought over the central terminal,the current will pass through resistance-section R, and when the leveris in contact with the third terminal the current will pass through bothsections. (See arrows, Fig. 1.)

The resistance B being convoluted, as shown, and of the same thicknessas the width of the grooves, is held securely in place by bindingagainst the walls thereof, yet it can be readily removed for repair orfor replacing the old wire with a new one. The width of the convo'lutesis preferably somewhat less than the depth of the groove.

It will be understood that the number of grooves and the number ofresistance-sections may be increased indefinitely without departing frommy invention. The grooves for the resistances occupy so little space insuperficial area that a great number of resistance-sections may besecured in a plate of small size.

Having now fully described my invention, what I claim, and desire toprotect by Letters Patent, is-

1. A rheostat or resistance plate, having grooves, in combination with aresistancewire bent upon itself to form a convolute and held in placewithin the grooves by compres sion against the walls thereof,substantially as described.

2. In a rheostat or resistance, the combination with a plate, ofbinding-posts and terminals secured thereto, said plate having verticalgrooves connecting the terminals, a lever adapted to be brought incontact with said terminals, electrical connection between onebinding-post and one of the terminals, and between the otherbinding-post and the lever, and a convoluted resistance held in placewithin the grooves by compression against the walls thereof andconnecting the terminals one with the other, substantially as described.

3. Arheostat or resistance plate having terminals on its upper face,grooves on its under face extending from the edge of the plate to pointsopposite said terminals, one of said grooves extending at an angle toand opening into the others, in combination with resistance-sectionsconnecting adjacent terminals, each of which extends through two of saidgrooves, and through a portion of the length of the common intersectinggroove, said resistance-sections being held in place within the groovesby compression against the walls thereof, substantially as described.

4. A rheostat or resistance plate having a series of terminals on itsupper face,and grooves on its under side terminating at points oppositesaid terminals, there being one groove for the end terminals of theseries, and two grooves for each central terminal, the plate havinganother groove common to all the grooves leading to the terminals,resistancesections connecting adjacent terminals, each of which extendsthrough two of said grooves, and through a portion of the length of thecommon intersecting groove, said resistancesections being held in placewithin the grooves by compression against the walls thereof,substantially as described.

In testimony of which invention I have hereunto set my hand.

JOSEPH P. BALL. \Vitnesses:

FRANK S. BUssnR, CAROL. H. DESHONG.

